Thank you, Craig, and good afternoon, everyone. Before I begin my prepared remarks, I'd like to call your attention to our 2020 third quarter earnings press release that was issued earlier this morning. If you need a copy, it can be accessed on our website at ashs.com at press releases under the Investors tab.
Now turning to our third quarter results. For the 3 months ended September 30, 2020, total revenues decreased 11.9% to $4.670 million compared to total revenue of $5.301 million for the third quarter of 2019 and increased 17% compared to total revenue of $3.991 million for the second quarter of 2020. The company recorded no revenue from its IGRT equipment in the current quarter compared to $314,000 in the third quarter of 2019. The equipment was fully depreciated and sold in July after expiration of the company's contract.
Third quarter revenue for the company's Proton therapy system installed at Orlando Health in Florida increased 0.6% to $1.687 million compared to revenue for the third quarter of 2019 of $1.677 million and increased 20.4% compared to revenue of $1.401 million in the second quarter of 2020. The year over year increase was due to higher volumes, offset by a lower average reimbursement for fraction.
Average reimbursement for fraction was consistent with the second quarter of 2020. Total proton therapy fractions in the third quarter were 1,632, an increase of 12.4% compared to 1,452 proton therapy fractions in the third quarter of 2019 and an increase of [ 20.8 ] compared to 1,351 in the second quarter of 2020.
Revenue for the company's Gamma Knife operations decreased 9.9% to $2.983 million for the third quarter of 2020 compared to $3.310 million for the third quarter of 2019 and and increased 15.2% compared to $2.59 million for the second quarter of 2020. The year over year decline was due to lower average reimbursement at the company's retail sites and a positive contractual adjustment related to Medicare reimbursement at one of the company's sites recognized in the prior year's third quarter.
Gamma Knife's procedures increased by 8.3% to $377 for the third quarter of 2020 from $348 in the same period of the prior year and 7.7% compared to $350 for the second quarter of 2020. The increase from the second quarter reflects the acquisition of Gamma Knife center Ecuador. Gamma Knife volumes for centers and operations decreased 8% from Gamma Knife volumes for the same centers during the same period of the prior year.
Gross margin for the third quarter of 2020 decreased to $1.138 million or 24.4% of revenue compared to gross margin of [ $1.830 million ] or 34.2% of revenue for the third quarter of 2019, an increase from $907,000 or 22.7% of revenue for the second quarter of 2020. Selling and administrative costs increased by $70,000 or 6.6% to $1.135 million for the third quarter compared to $1.065 million for the third quarter of 2019 and a decline of 6.2% compared to $1.210 million for the second quarter of 2020.
The year over year increase is due to tax, legal and consulting fees of [ $69,000 ] related to the company's acquisition of GK [indiscernible] . Net loss for the third quarter of 2020 was $209,000 or $0.03 per diluted share. This compares to net income for the third quarter of 2019 of $165,000 or $0.03 per diluted share and a net loss of $483,000 or $0.08 per diluted share for the second quarter of 2020. Fully diluted and weighted average common shares outstanding were 6.049 million and 5.908 million for the third quarter of 2020 and 2019, respectively.
Adjusted EBITDA, a non GAAP financial measure was [ $1.979 million ] for the third quarter of 2020 compared to $2.445 million for the third quarter of 2019 and $1.437 million for the second quarter of 2020. The year over year decline was primarily due to the reduction in overall income.
Turning to the balance sheet. Cash, cash equivalents and restricted cash was $3.983 million at September 30, 2020, compared to $1.779 million at December 31, 2019. This concludes the formal part of our presentation. Brandon, we'd now like to turn the call back over to you for questions.